Republicans had just passed a bill to repeal major portions of Obamacare without any Democratic support, and the minority party was convinced the vote would send them into the majority by January 2019.

Explore where you live.

Now, Democrats are trying to use healthcare to engineer a similar wave, and Miami Republican Rep. Carlos Curbelo's Miami-to-Key-West district is ground zero for their efforts. Curbelo won reelection in 2016 by 12 percentage points despite representing a Democratic-leaning district that voted for Hillary Clinton over Donald Trump by 16 percentage points, and his seat is a top priority for Democrats as they seek to win 24 seats to gain control of the House after the November elections.

On the one year anniversary of the House vote to pass the American Health Care Act, known as the AHCA, Democrats are spending millions to remind voters in districts like Curbelo's that their representative voted to essentially repeal Obamacare, the sweeping healthcare law passed solely by Democrats in 2009. Democrats are so confident that Curbelo's healthcare record will be his political undoing that House Minority Leader Nancy Pelosi traveled to South Miami-Dade on Thursday to appear with his Democratic opponent and trash his record.

"Today we’re talking about the one-year anniversary of a very destructive bill that the congressman from this area, Mr. Curbelo, voted for to the detriment of people in this district,” Pelosi said, adding that Curbelo's support for the GOP tax bill that became law late last year further eroded affordable healthcare by removing penalties for the individual mandate. “What they couldn’t achieve in the president’s [healthcare] bill, they tried to do some of in the tax bill. So elections have consequences. Legislation affects peoples’ lives. We’re just trying to show the connection."

Curbelo welcomes the attention on healthcare, and says his position on Obamacare hasn't changed since he first ran for Congress in 2013.

"We need to keep the good in the law. That means protections for those with preexisting conditions, doesn’t discriminate against women, and allow young people to stay on their parent's plans until they are established and can purchase their own health insurance," Curbelo said. "And we need to replace the bad with something that works better. A year later I still get some complaints in my office about the Affordable Care Act."

A year ago, it wasn't clear how Curbelo would vote on the final bill, which passed by just four votes after 20 Republicans, including Miami Rep. Ileana Ros-Lehtinen, voted against it. One day before the vote, Curbelo tweeted that the AHCA "in its current form fails to sufficiently protect Americans with pre-existing conditions."

I just reiterated to @HouseGOP leaders that #AHCA in its current form fails to sufficiently protect Americans with pre-existing conditions

But 24 hours later he voted for the bill, which some thought was because of arm-twisting by House Speaker Paul Ryan and GOP leadership, since the vote margin was going to be razor-thin. Curbelo says that wasn't the case.

"I actually was the one who informed House leaders how I would vote very late because we had some late-filed amendments that addressed some concerns a lot of us had," Curbelo said. "One of the reasons I took so long to make a decision is because some on the right really did want to undermine protections for those with pre-existing conditions."

But Curbelo doesn't have much to show for his tough vote. A scaled-down version of the AHCA that was tweaked to pass the U.S. Senate failed when Arizona Sen. John McCain, one of Curbelo's personal heroes, cast the decisive "no" vote. Portions of Obamacare were rolled back in the GOP tax bill that passed the House and Senate and became law in December 2017. Curbelo, a member of the House tax writing committee, played an important role in its passage and Democrats are also trying to use his support for that legislation against him in November.

Curbelo's congressional district has 92,500 people enrolled in Obamacare, the second-highest number of enrollees out of 435 districts around the country. Only Ros-Lehtinen's neighboring district has more. The sheer number of people who receive healthcare through Obamacare creates a natural constituency of motivated voters who can flip Curbelo's seat, said Topher Spiro, the vice president for health policy at the Center for American Progress, a left-leaning think tank.

Debbie Mucarsel-Powell

"I think all of the evidence we’ve seen is that healthcare is going to be a defining and motivating issue," said Spiro, who recently sparred with Curbelo on social media. "It's really just reminding people what happened last year."

Groups like Health Care Voter are planning to spend money and put boots on the ground in districts like Curbelo's and other competitive districts in Florida with Republicans who voted for the bill, like Miami Rep. Mario Diaz-Balart and Treasure Coast Rep. Brian Mast. But running a political operation in Miami is expensive, and Curbelo has $2.1 million to spend on his reelection campaign, along with outside groups that can spend millions to support him.

Spiro — who Curbelo said was "politically intoxicated" for saying that Curbelo's efforts to work with Democrats on smaller pieces of legislation related to healthcare were "empty words" — said Curbelo is "pretty sensitive to being called out."

Just off top of my head: most environmental votes, multiple CRs, conceal carry reprocity. But people like you aren’t interested in facts. Your political intoxication drives you to spread lies, half truths & attempt to radicalize others. You’re part of the problem. You’re #PIPhttps://t.co/EA5mvCNOhV

"His response was revealing because he likes to blame both sides for a political narrative that is polarizing," Spiro said. "Anyone who objectively looks at the situation knows that the polarization is coming from Trump and from Congress jamming through a massive healthcare bill and tax bill without any hearings. That's what's causing the polarization and Curbelo is a party to that."

Curbelo's likely Democratic opponent, Debbie Mucarsel-Powell, a former executive with the Florida International University Herbert Wertheim College of Medicine, said his vote to repeal Obamacare is what convinced her to run for Congress.

"I’ve spent most my career working to protect, expand healthcare in this community,” she said. “On May 4 of last year, when I saw Congressman Curbelo take that vote to threaten all of our work that we’ve done for so many years, that was a moment I knew it was very personal for me and that’s the moment I knew I had to step in and fight for healthcare for our community.”